The prior art, German OS No. 34 18 762, discloses a combustion engine fuel injection valve in which the fuel is discharged in metered quantities upstream of the sealing seat (internal metering). For this purpose the valve needle is provided with metering openings through which the fuel flows with an accompanying drop in pressure. However, the disadvantage of the described injection valve is that metering takes place in a region of the valve needle disposed far upstream and, as a result, the metered fuel must flow a long distance through extensive clearance before it is discharged. Rapid and accurate discharge of the fuel is thereby impaired.
German OS No. 34 18 761 discloses an injection valve which meters the fuel upstream of the sealing seat. However, rapid starting of the flow cannot be achieved with this valve either because after metering has taken place the fuel flows into the undercut zone resulting from the manufacturing process and it is there decelerated. The resulting flow turbulence prevents the rapid passage of the fuel to the discharge end. Accordingly, this valve also operates with a delayed discharge.